Defect Age

    DEFECT AGE is a measure of the difference between defect detection and defect injection. It can be measured in terms of Time or Phases.

    Defect Age (In Time)

    Definition

    Defect Age (in Time) is the difference in time between the date a defect is detected and the current date (if the defect is still open) or the date the defect was fixed (if the defect is already fixed).

    Elaboration

    • The ‘defects’ are confirmed and assigned (not just reported).
    • Dropped defects are not counted.
    • The difference in time can be calculated in hours or in days.
    • ‘fixed’ means that the defect is verified and closed; not just ‘completed’ by the developer.

    Defect Age Formula / Calculation

    Defect Age in Time = Defect Fix Date (OR Current Date) - Defect Detection Date

    Example

    If a defect was detected on 01/01/2009 10:00:00 AM and closed on 01/04/2009 12:00:00 PM, the Defect Age is 74 hours.

    Use

    • For determining the responsiveness of the development/ testing team. Lesser the age, better the responsiveness.

    Defect Age (In Phases)

    Definition

    Defect Age (in Phases) is the difference in phases between the defect injection phase and the defect detection phase.

    Elaboration

    • ‘defect injection phase’ is the phase in the software life cycle where the defect was introduced.
    • ‘defect detection phase’ is the phase in the software life cycle where the defect was identified.

    Defect Age Formula / Calculation

    Defect Age in Phase = Defect Detection Phase - Defect Injection Phase

    Example

    Let’s say the software life cycle has the following phases:

    1. Requirements Development
    2. High-Level Design
    3. Detail Design
    4. Coding
    5. Unit Testing
    6. Integration Testing
    7. System Testing
    8. Acceptance Testing

    If a defect is identified in System Testing and the defect was introduced in Requirements Development, the Defect Age is 6 (7-1). If a defect is identified in Acceptance Testing and it was introduced in Coding, the Defect Age is 4 (8-4).

    Use

    • For assessing the effectiveness of each phase and any review/ testing activities. Lesser the age, better the effectiveness.

    Goal

    The goal for Defect Age should be to maintain it at the lowest minimum number (whether in time or in phases).

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    Learn about a somewhat related and useful metric: DEFECT DETECTION EFFICIENCY.

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    Last Updated on September 6, 2020 by STF